1. Field of the Invention
The present invention relates to a camera exposure calculating apparatus which calculates a combination of a shutter speed and a diaphragm aperture value in conformance with a light measurement and a predetermined program and which modifies the combination in such a way as to cause the increase of one of the shutter speed and aperture values by an amount determined by a manual operation and decrease the other by the same amount.
2. Description of the Prior Art
A known camera exposure calculating device of the above mentioned type such as disclosed in a Japanese laid-open patent application with the laid-open No. 54-138431 is provided with a setting switch manually operable for setting a modification value, a modification calculating circuit for modifying the combination of the shutter speed and aperture value by an amount according to the modification value,and a reset switch operable for resetting the modification value to zero. In response to manual operation of the reset switch, the shutter speed and the aperture values are restored to of standard programmed value or the values set in advance of the modification operation.
In the configuration disclosed in the laid-open application, once a shutter speed and an aperture value are modified from the values determined by a standard programmed diagram, the modification values remain in a memory in the camera till the reset switch is operated or the setting switch for modifying the shutter speed and diaphragm aperture in the opposite direction is operated to make zero the memorized value.
If the camera is arranged to enable photography in an exposure mode other than the above mentioned programmed exposure mode, the following problem will occur when a photograph of a picture is taken with the above mentioned modified combination and a next picture subsequently in a different exposure mode. If the user intends to take another picture, subsequently to the photograph in the different exposure, with a shutter speed and aperture value according to the standard program diagram, the previous modification value will still remain in memory. In this case, the reset switch or the setting switch for the reversed direction modification must be operated. Accordingly the reset operation is complicated. Additionally, if the user takes a picture without resetting the modification value, a photograph contrary to the intention of the photographer will result. Furthermore, providing a reset switch in addition to the setting switch not only increases costs of the camera, but is further undesirable in increasing the camera size and weight.